Injection molding alignment steering utilizing sequential throttles in base-wall-section flow guides

ABSTRACT

During injection molding of a plastic product having a base wall and a sidewall, alignment of the mold parts that shape the mold cavity is maintained by conducting injected plastic material through a sequence of variable-opening throttles in a base-wall-section flow guide of the mold cavity. The openings of the throttles vary in response to variations in the thickness of a region of the sidewall section into which injected plastic material is conducted from the base-wall-section flow guide so that upon an increase in the thickness of such region the openings of the throttles in the base-wall-section flow guide decrease and so that upon a decrease in the thickness of such region the openings of the throttles in the base-wall-section flow guide increase.

BACKGROUND OF THE INVENTION

The present invention generally pertains to injection molding of plasticproducts and is particularly directed to adjusting flow of injectedplastic material and/or maintaining alignment of mold parts by steeringat least one of the mold parts during injection molding of a plasticproduct having a base wall and a sidewall.

Various methods and apparatus for adjusting flow of injected plasticmaterial and/or maintaining such an alignment by steering at least oneof the mold parts during injection of fluid plastic material aredescribed in U.S. Pat. No. 3,375,554 to Blumer, U.S. Pat. No. 3,397,266to Ayres, U.S. Pat. No. 3,829,548 to Edwards, U.S. Pat. No. 3,882,212 toEdwards, U.S. Pat. No. 3,995,008 to Spiegelberg, U.S. Pat. No. 4,264,295to Hingley, U.S. Pat. No. 4,467,994 to Sorensen and U.S. Pat. No.4,657,141 to Sorensen, U.S. Pat. No. 4,959,005 to Sorensen, and EuropeanPatent Publication No. 0 347 837 A2.

SUMMARY OF THE INVENTION

The present invention provides a method of injection molding a plasticproduct having a base wall and a sidewall, the method comprising thesteps of:

(a) shaping a mold cavity by combining a first mold part and a secondmold part in opposition to one another;

(b) injecting fluid plastic material into a base-wall section of a moldcavity; and

(c) conducting said injected plastic material through at least one flowguide in the base-wall section and thence into a sidewall section of themold cavity;

wherein step (a) comprises the step of:

(d) shaping a portion of a given said base-wall section flow guide bypartially opposing a row of recesses in the first mold part with a rowof recesses in the second mold part with the recesses in the first moldpart being so staggered with respect to the recesses in the second moldpart as to provide a chain of overlapping recesses that form a sequenceof variable-opening throttles having openings that can vary within thegiven flow guide whenever the alignment between the combined first andsecond mold parts varies in response to variations in the thickness of aregion of the sidewall section into which injected plastic material isconducted from the given flow guide so that upon an increase in thethickness of said region the openings of said throttles the given flowguide decrease and so that upon a decrease in the thickness of saidregion the openings of said throttles in the given flow guide increase.

For the purpose of interpreting this document, a flow guide is a portionof a mold cavity that conducts plastic material into an adjacent thinnerportion of the mold cavity and/or into another flow guide.

The present invention also provides a mold for injection molding aplastic product having a base wall and a sidewall, comprising: moldparts for shaping a mold cavity for forming the product and a gate fromwhich fluid plastic material can be injected into a base-wall section ofthe mold cavity; wherein the base-wall section includes at least oneflow guide for conducting said injected plastic material through thebase-wall section and thence into a sidewall section of the mold cavity;and wherein the mold parts include a first mold part that includes a rowof recesses and a second mold part that includes a row of recesses thatare partially opposed to the row of recesses in the first mold part toshape a portion of a given said base-wall section flow guide when thefirst and second mold parts are combined in opposition to one anotherwith the recesses in the first mold part being so staggered with respectto the recesses in the second mold part as to provide a chain ofoverlapping recesses that form a sequence of variable-opening throttles,having openings that can vary within the given flow guide whenever thealignment between the combined first and second mold parts varies inresponse to variations in the thickness of a region of the sidewallsection into which injected plastic material is conducted from the givenflow guide so that upon an increase in the thickness of said region theopenings of said throttles in the given flow guide decrease and so thatupon a decrease in the thickness of said region the openings of saidthrottles in the given flow guide increase.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a sectional view of a preferred embodiment of a mold accordingto the present invention, taken along line 1—1 in FIG. 2.

FIG. 1A is an enlarged view of encircled portion 1A of a mold cavityshown in FIG. 1, with said enlarged view illustrating the sectionalaspect of a sequence of variable-opening throttles in abase-wall-section flow guide.

FIG. 2 is an end view of the mold cavity within the mold of FIG. 1,taken along line 2—2 in FIG. 1, and illustrating the approximate broadbase-wall dimension aspect of the throttled flow guides shown in FIG.1A.

FIGS. 3A and 3B viewed together illustrate variation in the openings ofthe sequence of throttles in the base-wall-section flow guide of FIG.1A.

FIG. 4 illustrates one alternative embodiment of the sectional aspect ofa sequence of variable-opening throttles in a base-wall-section flowguide.

FIG. 5 illustrates another alternative embodiment of the sectionalaspect of a sequence of variable-opening throttles in abase-wall-section flow guide.

FIG. 6 illustrates one alternative embodiment of the broad base-wallsection aspect of a sequence of variable-opening throttles in abase-wall-section flow guide.

FIG. 7 illustrates another alternative embodiment of the broad base-wallsection aspect of a sequence of variable-opening throttles in abase-wall-section flow guide.

FIG. 8 is an end view of an alternative embodiment of a mold cavity thatfurther contains concentric flow guides intersecting with radialthrottled base-wall-section flow guides.

FIG. 9, which is taken along line 9—9 in FIG. 8, illustrates thesectional aspect of the sequence of variable-opening throttles in theindividual base-wall-section flow guides in the embodiment of FIG. 8.

FIG. 10 is an end view of another alternative embodiment of a moldcavity that further contains concentric flow guides intersecting withradial throttled base-wall-section flow guides.

FIG. 11, which is taken along line 11—11 in FIG. 10, illustrates thesectional aspect of the sequence of variable-opening throttles in theindividual base-wall-section flow guides in the embodiment of FIG. 10.

FIG. 12, which is taken along line 12—12 in FIG. 11, illustrates anothersectional aspect of a variable-opening throttle in the embodiment ofFIGS. 10 and 11.

FIG. 13 is a side view of a flow guide in combination with a movablemold part for adjusting conduction within the flow guide.

FIG. 14 is a top view of the flow guide of FIG. 13.

DETAILED DESCRIPTION

Referring to FIG. 1, a preferred embodiment of the mold 10 includes acore mold part 12, a stationary cavity mold part 14 and an adjustablecavity mold part 16 for shaping a mold cavity 18 for forming a hollowsymmetrical thin-wall plastic product, such as a drink cup, and a gate20 from which fluid plastic material can be injected into a base-wallsection 22 of the mold cavity 18 when the adjustable cavity mold part 16and the core mold part 12 are combined in an aligned opposition to oneanother. At least three screws 23 are symmetrically disposed adjacentthe side of the adjustable cavity mold part 16 for initializing theposition of the adjustable cavity mold part 16 to adjust the alignmentbetween the adjustable cavity mold part 16 and the core mold part 12.

In an alternative embodiment (not shown), the adjustable cavity moldpart is attached to a symmetrical plurality of at least three pistonswithin a corresponding plurality of hydraulic cylinders for variablepositioning of the adjustable cavity mold part in order to adjust thealignment between the adjustable cavity mold part and the core moldpart. The position of the adjustable cavity mold part is initializedprior to commencement of a production run; and in some, but not allembodiments, (not shown) the position of the adjustable cavity mold partis also varied dynamically during a production run by varying therelative hydraulic fluid flows and/or pressures in the respectivecylinders to further adjust the alignment between the adjustable cavitymold part and the core mold part in response to variations in injectionpressures in different portions of the sidewall section of the moldcavity as sensed by a plurality of symmetrically disposed side moldpressure sensors. The variations of the relative hydraulic fluid flowsand/or pressures in response to the sensed variations in thesidewall-section injection pressures are controlled by a computer.

In another alternative embodiment (not shown), the mold 10 does notinclude an adjustable cavity mold cavity part for shaping any portion ofthe base-wall section 22. In this alternative embodiment, the moldcavity is shaped by a combination of a core mold part and a stationarycavity mold part.

Referring to FIG. 1, a preferred embodiment of the mold 10 includes acore mold part 12, a stationary cavity mold part 14 and an adjustablecavity mold part 16 for shaping a mold cavity 18 for forming a hollowsymmetrical thin-wall plastic product,

Referring to FIGS. 1A and 2, the mold cavity 18 includes the base-wallsection 22 and a sidewall section 24. The base-wall section 22 includesan inlet section 25 adjacent the gate 20, an inner circular flow guide26 encircling the inlet section 25 and a plurality of radial flow guides28 for conducting the injected plastic material from the inner circularflow guide 26, through the base-wall section 22 and thence into thesidewall section 24.

Each of the base-wall-section flow guides 28 includes a sequence ofvariable-opening throttles 30 through which the injected plasticmaterial is conducted to the sidewall section 24. The sidewall section24 includes a plurality of thin-wall sectors 31 and a plurality of flowguides 32 respectively extending from the plurality of throttledbase-wall-section flow guides 28 for directing the flow of some of theinjected plastic material to the thin-wall sectors 31 of thesidewall-section 24.

The throttles 30 are formed by an overlapping chain of recesses, whichare provided by partially opposed rows of recesses 33, 34 in therespective combined core mold part 12 and adjustable cavity mold part16, with the opposed recesses 33, 34 being so staggered along thedirection of conduction 36 within a given individual base-wall-sectionflow guide 28 that whenever the alignment between the combined core moldpart 12 and the adjustable cavity mold part 16 varies along thedirection of conduction 36 for the given flow guide 28 the openings ofthe throttles 30 in the given flow guide 28 vary. The recesses 33, 34are circular in the approximate broad dimension of the base-wail section22, as shown in FIG. 2. The width A of a given throttle 30 is less thanthe width B of the overlapping recesses 33, 34 that form the giventhrottle 30.

The opening distance of an individual throttle 30 is equal to the squareroot of the sum of the square of the minimum width W of the stagger ofthe opposed recesses 33, 34 and the square of the separation S betweenthe combined core mold part 12 and the adjustable cavity mold part 16 inthe region of minimum stagger of the opposed recesses 33, 34.Preferably, in order to inhibit damage to the opposed core mold part 12and adjustable cavity mold part 16 when the mold is compressed by arequisite clamping force, the shortest distance of separation within themold cavity 18 in the direction of mold closure 40 when the mold is notclamped is larger than the elastic compression distance of the moldcavity 18 when the mold 10 is compressed by the requisite clampingforce.

Referring to FIGS. 3A and 3B, the openings of the throttles 30 in agiven base-wall-section flow guide 28 can vary in response to variationsin the thickness of a region 42 of the sidewall section 24 into whichthe plastic material is conducted from the given base-wall-section flowguide 28 so that upon an increase in the thickness of the sidewallregion 42, and thereby the thickness T of the adjacent sidewall sector31, the openings of the throttles 30 in the given base-wall-section flowguide 28 decrease (FIG. 3A) and so that upon a decrease in the thicknessof the sidewall region 42, and thereby the thickness T of the adjacentsidewall sector 31, the openings of the throttles 30 in the givenbase-wall-section flow guide 28 increase (FIG. 3B).

In an alternative embodiment (not shown) the mold cavity 18 furtherincludes a plurality of radial base-wall section flow guides that extendto the sidewall section 24 for conducting fluid plastic material intothe sidewall section 24 but do not include a sequence ofvariable-opening throttles; and the sidewall section 24 includes aplurality of flow guides 32 that extend from the non-throttled radialbase-wall section flow guides for directing the flow of some of theinjected plastic material to the thin-wall sectors 31 of thesidewall-section 24. The non-throttled radial base-wall section flowguides are interspersed symmetrically with the throttled radialbase-wall section flow guides 28.

In alternative embodiments, the throttles shaped by the opposed recessesin the combined core mold part 12 and adjustable cavity mold part 16have different configurations than the configuration shown in FIGS. 1A,2, 3A and 3B.

Referring to FIG. 4, portions 44′ of the core mold part 12′ disposedbetween the recesses 33′ extend into the recesses 34′ within theadjustable cavity mold part 16′ to thereby extend the length of theopenings of the throttles 30′ in contrast to the embodiment shown inFIG. 1A.

Referring to FIG. 5, portions 44″ of the core mold part 12″ disposedbetween the recesses 33″ extend into the recesses 34″ within theadjustable cavity mold part 16″ and portions 46″ of the adjustablecavity mold part 16″ disposed between the recesses 34″ extend into therecesses 33″ within the core mold part 12″ to thereby further extend thelength of the openings of the throttles 30″ in contrast to theembodiments shown in FIGS. 1A and 4.

Referring to FIG. 6, the recesses 133, 134 within the respective coremold part and adjustable cavity mold part are approximately rectangularin the approximate broad dimension of the base-wall section and aredisposed with opposite corners of the rectangles aligned along thedirection of conduction 136 within the flow guide 128 so that thecorners of the recesses 133 within the core mold part are staggered withthe corners of the recesses 134 within the adjustable cavity mold partto thereby shape the openings of the variable-opening throttles 130.

The width A of a given throttle 130 is less than the width B of theoverlapping recesses 133, 134 that form the given throttle 130.

Referring to FIG. 7, the recesses 233, 234 within the respective coremold part and adjustable cavity mold part are approximately rectangularin the approximate broad dimension of the base-wall section and aredisposed with opposite sides of the rectangles aligned along thedirection of conduction 236 within the flow guide 228 so that the sidesof the recesses 233 within the core mold part are staggered with thesides of the recesses 234 within the adjustable cavity mold part tothereby shape the openings of the variable-opening throttles 230.

The width A of a given throttle 230 is not more than the width B of theoverlapping recesses 233, 234 that form the given throttle 230.

Referring to FIGS. 8 and 9, an alternative embodiment of the mold cavity18 further contains a plurality of concentric flow guides 48 disposedbetween the inner circular flow guide 26 and the sidewall section 24.The concentric flow guides 48 intersect with the plurality of throttledradial base-wall-section flow guides 28. The concentric flow guides 48inhibit the injected fluid plastic material from being conducted to thesidewall section 24 of the mold cavity 18 through the thin-wall sectors49 of the base-wall section 22 that lie between the radial flow guides28 and the concentric flow guides 48.

A preferred embodiment of the mold cavity 18 is shown in FIGS. 10, 11and 12. The mold cavity 18 includes the base-wall section 50 and asidewall section 52. The base-wall section 50 includes an inner circularflow guide 56, a plurality of inlet flow guides 58 extending from a gateto the inner circular flow guide 56, a plurality of throttled radialflow guides 60 and a plurality of concentric flow guides 62 disposedbetween the inner circular flow guide 56 and the sidewall section 52.

The throttled radial flow guides 60 conduct the injected plasticmaterial from the inner circular flow guide 56, through the base-wallsection 50 and thence into the sidewall section 52. The concentric flowguides 62 intersect with the plurality of throttled radialbase-wall-section flow guides 60 and inhibit the injected fluid plasticmaterial from being conducted to the sidewall section 52 of the moldcavity 18 through the thin-wall sectors 63 of the base-wall section 50that lie between the radial flow guides 60.

Each of the radial base-wall-section flow guides 60 includes a sequenceof variable-opening throttles 64 through which the injected plasticmaterial is conducted to the sidewall section 52. The sidewall section52 includes a plurality of thin-wall sectors 66 and a plurality of flowguides 68 respectively extending from the plurality of throttledbase-wall-section flow guides 60 for directing the flow of some of theinjected plastic material to the thin-wall sectors 66 of thesidewall-section 52.

The throttles 64 are formed by an overlapping chain of recesses, whichare provided by partially opposed rows of recesses 70, 72 in therespective combined core mold part 12 and adjustable cavity mold part16, with the opposed recesses 70, 72 being so staggered along thedirection of conduction 74 within a given individual radialbase-wall-section flow guide 60 that whenever the alignment between thecombined core mold part 12 and the adjustable cavity mold part 16 variesalong the direction of conduction 74 for the given flow guide 60 theopening of the throttles 64 in the given flow guide 60 vary. Therecesses 70, 72 are approximately rectangular in the approximate broaddimension of the base-wall section 50, as shown in FIG. 10, and aredisposed with opposite sides of the rectangles aligned along thedirection of conduction 74 within an individual flow guide 60 so thatthe sides of the recesses 70 within the core mold part are staggeredwith the sides of the recesses 72 within the adjustable cavity mold partto thereby shape the openings of the variable-opening throttles 64.

In the preferred embodiment of FIGS. 10, 11 and 12, the mold cavity 18further includes chambers 80 adjacent the sidewall-section periphery ofthe base-wall section 50 at the junctures of the plastic materialdirected into the thin-wall cavity sectors 63 by the flow guides 60adjacent the thin-wall cavity sectors 63 for forming ridges on theinside of the base wall of the injection-molded product to therebyenhance the stiffness of the base wall of the product.

Referring to FIGS. 13 and 14 the alignment of the mold parts duringinjection is further enhanced in some, but not all, embodiments byutilization of a movable channel mold part 82 that is disposed in anintroductory portion of one or more of the throttled radial flow guidesbetween the inner circular flow guide and the beginning of the sequenceof throttles. When the movable channel mold part 82 is so utilized theintroductory portion of the throttled flow guide includes a firstsegment 84 and a second segment 86 that is misaligned with the firstsegment 84 but that overlaps the first segment 84 to enable conductionof fluid plastic material from the first segment 84 to the secondsegment 86. The movable channel mold part 82 is disposed at the segmentoverlap to decrease the overlap when the movable channel mold part 82 isprotracted and to increase the overlap when the movable channel moldpart 82 is retracted, to thereby adjust the conduction of fluid plasticmaterial within the flow guide.

The movable channel mold part 82 is attached to a piston 88 within ahydraulic cylinder 90 for protraction and retraction in response torelative hydraulic fluid flows and/or pressures within the front andback portions 92, 94 of the cylinder 90. The movable channel mold part82 is protracted or retracted to an initial position prior tocommencement of a production run. In some, but not all embodiments, (notshown) the movable channel mold part 82 is also protracted and/orretracted dynamically during a production run by varying the relativehydraulic fluid flows and/or pressures within the cylinder 90 inresponse to variations in injection pressures in different portions ofthe sidewall section 24 of the mold cavity 18 as sensed by a pluralityof symmetrically disposed side mold pressure sensors. The variations ofthe relative hydraulic fluid flows and/or pressures in response to thesensed variations in the sidewall-section injection pressures arecontrolled by a computer.

In another alternative embodiment (not shown), in which it is notdesired to dynamically protract and/or retract the movable channel moldpart 82 during a production run, a hydraulic-cylinder is not used.Instead a screw is connected to the movable channel mold part 82 forprotracting or retracting the movable channel mold part to an initialposition prior to commencement of a production run.

The movable channel mold part and flow guide combination of FIGS. 13 and14 is also useful for adjusting fluid plastic material conduction withinnon-throttled flow guides in injection molding embodiments unrelated toalignment of mold parts.

Additional embodiments of the present invention (not shown) include alldifferent combinations of the features described herein for adjustingflow of injected plastic material and/or aligning mold parts to shapeproducts that are not necessarily hollow or symmetrical.

The advantages specifically stated herein do not necessarily apply toevery conceivable embodiment of the present invention. Further, suchstated advantages of the present invention are only examples and shouldnot be construed as the only advantages of the present invention. Whilethe above description contains many specificities, these should not beconstrued as being necessarily required for use of the present inventionor as limitations on the scope of the present invention, but rather asexamples of the embodiments described herein. Other variations arepossible and the scope of the present invention should be determined notby the embodiments described herein but rather by the claims and theirlegal equivalents.

1. A method of injection molding a plastic product having a base walland a sidewall, the method comprising the steps of: (a) shaping a moldcavity by combining a first mold part and a second mold part inopposition to one another; (b) injecting fluid plastic material into abase-wall section of a mold cavity; and (c) conducting said injectedplastic material through at least one flow guide in the base-wallsection and thence into a sidewall section of the mold cavity; whereinstep (a) comprises the step of: (d) shaping a portion of a given saidbase-wall section flow guide by partially opposing a row of recesses inthe first mold part with a row of recesses in the second mold part withthe recesses in the first mold part being so staggered with respect tothe recesses in the second mold part as to provide a chain ofoverlapping recesses that form a sequence of variable-opening throttleshaving openings that can vary within the given flow guide whenever thealignment between the combined first and second mold parts varies inresponse to variations in the thickness of a region of the sidewallsection into which injected plastic material is conducted from the givenflow guide so that upon an increase in the thickness of said region theopenings of said throttles in the given flow guide decrease and so thatupon a decrease in the thickness of said region the openings of saidthrottles in the given flow guide increase.
 2. A method according toclaim 1, further comprising the step of: (e) within the sidewall sectionof the mold cavity, directing the flow of some of the injected plasticmaterial by means of at least one sidewall-section flow guide.
 3. Amethod according to claim 1, further comprising the step of: (e) withinthe sidewall section of the mold cavity, directing the flow of some ofthe injected plastic material by means of a sidewall-section flow guidethat extends from said at-least-one base-wall-section flow guide.
 4. Amethod according to claim 1, wherein step (c) comprises conducting saidinjected plastic material through a plurality of said throttledbase-section flow guides and thence into the sidewall section of themold cavity.
 5. A method according to claim 4, wherein the methodfurther comprises the step of: (e) directing the injected fluid plasticmaterial into thin-wall cavity sectors of the base-wall section tochambers adjacent the sidewall-section periphery of the base-wallsection at a juncture of the plastic material directed into thin-wallcavity sectors of the base-wall section by the flow guides adjacent thethin-wall cavity sectors to thereby form ridges on the inside of thebase wall of the injection-molded product.
 6. A method according toclaim 4, further comprising the step of: (e) within the sidewall sectionof the mold cavity, directing the flow of some of the injected plasticmaterial by means of sidewall-section flow guides that extendrespectively from a plurality of said throttled base-wall-section flowguides.
 7. A method according to claim 1, wherein the width of a givensaid throttle is not more than the width of the overlapping recessesthat form the given throttle.
 8. A method according to claim 1, whereinthe width of a given said throttle is less than the width of theoverlapping recesses that form the given throttle.
 9. A method accordingto claim 1, wherein the base-wall section includes a plurality of saidthrottled flow guides that extend radially for conducting said injectedplastic material through the base-wall section and thence into thesidewall section of the mold cavity; further comprising the step of: (e)conducting the injected plastic material within the base-wall section bymeans of a plurality of concentric flow guides that intersect theradially extending flow guides.
 10. A method according to claim 1,further comprising the step of: (e) adjusting said conduction within theat-least-one base-wall-section flow guide by protracting a movable moldpart into said flow guide or by retracting a movable mold part from saidflow guide.
 11. A method according to claim 1, wherein the mold partsinclude an adjustable cavity mold part and a core mold part for shapingat least a portion of the base-wall section of the mold cavity when theadjustable cavity mold part and the core mold part are combined inopposition to one another; the method further comprising the step of:(e) initializing the position of the adjustable cavity mold part toadjust the alignment between the adjustable cavity mold part and thecore mold part.
 12. A method according to claim 11, further comprisingthe step of: (f) dynamically varying the position of the adjustablecavity mold part to further adjust the alignment between the adjustablecavity mold part and the core mold part.
 13. A method according to claim1, wherein the mold parts include an adjustable cavity mold part and acore mold part for shaping at least a portion of the base-wall sectionof the mold cavity when the adjustable cavity mold part and the coremold part are combined in opposition to one another; the method furthercomprising the step of: (e) dynamically varying the position of theadjustable cavity mold part to adjust the alignment between theadjustable cavity mold part and the core mold part.
 14. A methodaccording to claim 1, further comprising the step of: (e) shaping themold cavity by combining opposed first and second mold parts in adirection of mold closure; and wherein the shortest distance within themold cavity in said direction of mold closure is larger than the elasticcompression distance of the mold cavity when the mold is compressed by arequisite clamping force.
 15. A mold for injection molding a plasticproduct having a base wall and a sidewall, comprising: mold parts forshaping a mold cavity for forming the product and a gate from whichfluid plastic material can be injected into a base-wall section of themold cavity; wherein the base-wall section includes at least one flowguide for conducting said injected plastic material through thebase-wall section and thence into a sidewall section of the mold cavity;and wherein the mold parts include a first mold part that includes a rowof recesses and a second mold part that includes a row of recesses thatare partially opposed to the row of recesses in the first mold part toshape a portion of a given said base-wall section flow guide when thefirst and second mold parts are combined in opposition to one anotherwith the recesses in the first mold part being so staggered with respectto the recesses in the second mold part as to provide a chain ofoverlapping recesses that form a sequence of variable-opening throttleshaving openings that can vary within the given flow guide whenever thealignment between the combined first and second mold parts varies inresponse to variations in the thickness of a region of the sidewallsection into which injected plastic material is conducted from the givenflow guide so that upon an increase in the thickness of said region theopenings of said throttles in the given flow guide decrease and so thatupon a decrease in the thickness of said region the openings of saidthrottles in the given flow guide increase.
 16. A mold according toclaim 15, wherein the sidewall section of the mold cavity includes atleast one flow guide for directing the flow of some of the injectedplastic material.
 17. A mold according to claim 15, wherein saidat-least-one sidewall-section flow guide extends from said at-least-onebase-wall-section flow guide.
 18. A mold according to claim 15, whereinthe base-wall section includes a plurality of said throttled flow guidesfar conducting said injected plastic material through the base-wallsection and thence into the sidewall section of the mold cavity.
 19. Amold according to claim 18, wherein the sidewall section includes aplurality of flow guides respectively extending from a plurality of saidthrottled base-wall-section flow guides for directing the flow of someof the injected plastic material within the sidewall-section.
 20. A moldaccording to claim 18, wherein the mold cavity further includes chambersadjacent the sidewall-section periphery of the base-wall section at ajuncture of the plastic material directed into thin-wall cavity sectorsof the base-wall section by flow guides adjacent the thin-wall cavitysectors for forming ridges on the inside of the base wall of theinjection-molded product.
 21. A mold according to claim 15, wherein thewidth of a given said throttle is not more than the width of theoverlapping recesses that form the given throttle.
 22. A mold accordingto claim 15, wherein the width of a given said throttle is less than thewidth of the overlapping recesses that form the given throttle.
 23. Amold according to claim 15, wherein the base-wall section includes aplurality of said throttled flow guides that extend radially forconducting said injected plastic material through the base-wall sectionand thence into the sidewall section of the mold cavity and a pluralityof concentric flow guides that intersect the radially extending flowguides.
 24. A mold according to claim 15, wherein the mold parts includea movable mold part that is disposed for protraction into and retractionfrom the at-least-one base-wall-section flow guide for adjusting saidconduction within said flow guide.
 25. A mold according to claim 15,wherein the mold parts include an adjustable cavity mold part and a coremold part for shaping at least a portion of the base-wall section of themold cavity when the adjustable cavity mold part and the core mold partare combined in opposition to one another; the mold further comprising:means for initializing the position of the adjustable cavity mold partto adjust the alignment between the adjustable cavity mold part and thecore mold part.
 26. A mold according to claim 25, further comprising:means for dynamically varying the position of the adjustable cavity moldpart to adjust the alignment between the adjustable cavity mold part andthe core mold part.
 27. A mold according to claim 15, wherein the moldparts include an adjustable cavity mold part and a core mold part forshaping at least a portion of the base-wall section of the mold cavitywhen the adjustable cavity mold part and the core mold part are combinedin opposition to one another; the maid further comprising: means fordynamically varying the position of the adjustable cavity mold part toadjust the alignment between the adjustable cavity mold part and thecore mold part.
 28. A mold according to claim 15, wherein the moldcavity is shaped by combining opposed first and second mold parts in adirection of mold closure; and wherein the shortest distance within themold cavity in said direction of mold closure is larger than the elasticcompression distance of the mold cavity when the mold is compressed by arequisite clamping force.